This Application claims the priority of German Patent Application Serial Number 198.46.491.6, filed Oct. 9, 1999 and International Patent Application Serial Number PCT/EP99/07575 having an international filing date of Oct. 8, 1999 the entire contents of both of which are incorporated rein by reference.
1. Field of Invention
The invention relates to a current conducting rail.
2. Description of Related Art
Current conducting rails for supplying of mobile consumers that are comprised of two different materials are known in the art in numerous embodiments. Said conductor rails are comprised mainly of a base body onto which a sliding surface comprised of especially wear-resistant metal is applied. The German utility model 7114522 demonstrates such a conductor rail comprised of a base body made of metal which exhibits a head in which the sliding surface is folded around the head of the base body.
DT 2349127 discloses to the art a conductor rail for current consumers with high current demand and high travel speed, which exhibits a connector on the side facing the base body and which exhibits undercuts. The sliding surface body together with its contact is inserted at the narrow facial surface of the base into a corresponding groove in the base body that corresponds to the contact. Thereupon the external limbs of the sliding surface are bent against the corresponding sides of the base body using rollers acting upon them. At the same time the sides of the groove of the base body are pressed against the connector such that a permanent connection between the sliding surface and the base body is created.
Similarly, the German patent 2244452 discloses a current rail for the supply of current to movable current consumers with high current requirements and high speeds in which a slide surface comprised of a particularly wear-resistance metal is arranged on the base body. The base body exhibits on its side facing the slide surface a number of dove-tail projections over the length of the base body whereby said projections are engaged by U-shaped recesses in the web of the base body, whose flanks are engaged against the corresponding flanks of the projections on the base body. In the joining process, using rollers, which on the one hand presses together the slide surface serving as the current collector and the lateral wall of the base body to be joined with the slide rail, whereby the walls of the contact situated in the U-shaped recesses of the slide rail are pressed against the corresponding dove-tailed projections. At the same time the outer connecting pieces of the slide rail are engaged against the flanks of the base body in the customary manner using rollers.
The disadvantage in the current rails described in the foregoing is that the slide current conductor material which is always harder than that of the base body, is deformed, whereby there is no optimal adaptation can be produced between the softer material of the base body and the current conductor material at the time of roller shaping. Due to the fact that the current conductor, especially at its outer surfaces, does not optimally lie on the base body material, moisture can intrude between the two parts.
The purpose of the invention is to provide a current rail with a wear-resistant slide surface that is applied mechanically to the softer base body and in which corrosion does not form between the base body and the slide surface.
This purpose is achieved by a current rail having the characteristics described in claim 1. The current rail described in the invention is characterized by the fact that generally the softer material of the base body deforms and consequently a better connection between base body and slide surface is established. Corrosion formation, which could occur in current rails after the current state of technology whereby moisture from outside could at any time intrude between the base body and the slide surface laterally into the current rail is confronted in that the softer material of the base body, which is made especially of aluminum, is in cross-section is securely rolled onto the external surface or the outside edge of the harder slide surface piece. If, in the case of conventional current rails the base body is laterally wrapped by the harder slide surface material, then in the solution provided by the instant invention the softer material of the base body is pressed onto the harder material of the slide surface.
In order to achieve an optimum fastening between the structures of the base body and slide surface, connecting pieces are formed along the current rail at the slide surface that are especially provided with back-cuts. In the joining process the softer material of the base body is pressed behind the back-cuts, whereby a durable connection between base body and slide surface is achieved.
An advantageous connection between the base body and the slide surface is achieved especially when the base body is made of aluminum and the slide surface is made of stainless steel or copper. The forming of the aluminum base body is advantageously applied in the application in which even a light cold-hardening, but no embrittlement of the aluminum occurs.
In one possible embodiment, all connecting pieces have back-cuts only on one side. On the side of the connecting pieces facing the back-cuts there are slightly conical surfaces with an slope angle of about two degrees. On the side of the base body facing the slide surface structure a plurality of recesses are provided into which the connecting pieces engage prior to the forming process. The recesses are formed slightly conical, whereby the aperture cross-section is larger than the floor cross-section. The aperture angle of the conically arranged side walls likewise are approximately two degrees.
The inside surfaces of the longitudinal recess exhibit in a preferred embodiment longitudinal grooves. Inasmuch as an aluminum structure is used as the base body, a micrometer thin oxide layer always develops. By said grooving said oxidation layer is removed during the joining process, whereby a very satisfactory electrical contact is established between the base body and the slide surface. It is of further advantage if the connecting pieces have a greater peak-to-valley height than the slide surface itself, whereby a very satisfactory bond between the base body and the slide surface material is produced.
For the joining process a roller presses the slide surface material against the base body. A profiled roller presses at the same time the base body against the slide surface structure. In this way, the connecting pieces are pressed into the recesses , whereby the conical surfaces of the recesses and the connecting pieces are compressed against each other. Due to the compression pressure the grooving deforms and adapts to the contour of the shape of the connecting pieces. In the process, the oxidation layer of the aluminum structure is pulled away in the area of the grooving. Another spontaneous oxidation, which would proceed in a few minutes, is prevented by the satisfactory fit between the base body and the slide surface.
In order that the base body material is pressed into the space behind the back-cuts of the connecting pieces of the slide surface structure, a heavily profiled roll is used that is brought to rest on the side of the base body facing away from the slide surface structure.
By means of additional rolls that provide a lateral pressure against the material of the base body, the material is pressed into the recesses facing outward that are formed by the back-cuts of the outside connecting pieces and the long narrow sides of the slide surface. This provides a smooth transition between the material of the base body and that of the slide surface that prevents the intrusion of moisture between the two parts.
In order to prevent unnecessary additional tolerance, it is advantageous if the profiled parts, base body and slide surface, during their extrusion production process, are provided with rolled-in grooves to assure uniform lateral alignment.
Since, in the inventive current rail it is also possible that moisture can penetrate at the current rail end into the interspace between the slide surface and the base body, in a particular embodiment of the invention a contact mass is introduced prior to the joining process between the base body structure and the slide surface structure for the purpose of corrosion prevention, said mass is distributed in the joining process evening and over the entire contact surface.